Imaging Mass Spectrometry, which takes advantage of the methodology and instrumentation of matrix-assisted laser desorption ionization (MALDI) mass spectrometry, is a relatively new technology. Preliminary work has shown that it can be used to locate specific molecules such as peptides and proteins up to about 80,000 Daltons, directly from fresh frozen tissue or blots of this tissue. The data from such an analysis is a pictograph in real x,y dimensions on the tissue sample of the location of a signal at any given molecular weight. It has been shown to be effective for the analysis of proteins and peptides in normal and tumor tissue in mouse models of cancer and some human tumor samples. We propose to further develop instrumentation, specifically targeted to imaging and profiling proteins in mouse models and appropriate human samples of prostate, colon and brain cancer. The goals of the technology development are increasing the speed of analysis and sample throughput, and developing advanced data analysis and interpretation methods. Application to cancer research will take place through close collaboration with three investigators who have routine access to tumor tissue. The general goals of these applications are; 1) comparison of molecular weight based protein patterns determined by mass spectrometry in tumors versus normal tissues; 2) identify and image potential tumor markers using mass spectrometry; and 3) compare protein patterns obtained by mass spectrometry and identify unique proteins in various stages of precursor lesions in these three cancer models.